Moisture-permeable waterproof coated fabric

ABSTRACT

A moisture-permeable waterproof coated fabric having a microporous polyurethane layer is obtained by the so-called wet coagulation method using as a coated solution a polar organic solvent solution containing 8 to 25% by weight of a polyurethane elastomer, 0.1 to 10% by weight of a water repellent agent, 0.2 to 3% by weight of polyisocyanate and 1 to 8% by weight of a nonionic surfactant.

This is a division of application Ser. No. 286,615, filed on July 24,1981, now U.S. Pat. No. 4,429,000, which is a continuation of Ser. No.102,410, filed Dec. 11, 1979, now abandoned.

FIELD OF THE INVENTION

This invention relates to a moisture-permeable waterproof coated fabric.More particularly, it is concerned with a moisture-permeable waterproofcoated fabric of a drape handling having an excellent moisturepermeability, a moderate air permeability and a durable water-proofness,and method of making same.

BACKGROUND OF THE INVENTION

Various waterproof coated fabrics have heretofore been made public; forexample, waterproof fabrics coated with a natural or synthetic rubberare practically used for raincoats and other waterproof clothing, tents,tarpaulins and other products. But all of them are less moisturepermeable; for example, such a waterproof clothing as raincoat gives anunpleasant feeling in wear due to stuffiness, while in the case of tentsor the like there condenses vapor in the interior thereof in theirpractical use. On the other hand, as a waterproof fabric emphasizingmoisture permeability there is a fabric having high woven density with amere water repellent treatment applied thereto, but its water entrypressure is insufficient, about 100 mmH₂ O/cm² at the highest, becauseit is almost decided by the woven construction and yarn density of thefabric used, and when the durability of water repellency is taken intoaccount, its water-proofness is only temporary, for which reasons suchfabric is inappropriate as a practical waterproof fabric.

As a coated fabric having air- and moisture permeability, moreover,there is a fabric coated with a microporous polyurethane layer or afabric coated with a porous layer obtained by using a synthetic resinwith various blowing agents or the like added. The former is producedfor example by the so-called wet coagulation method in which a polarorganic solvent solution of a polyurethane is applied to a base fabricand then the latter is immersed in water bath to form a microporouspolyurethane layer thereon. According to this method, it is easy to forma layer having many fine pores, so air- and moisture permeability can beimparted easily, but it is difficult to attain a necessary andsufficient water-proofness. As an example of method of making thelatter, mention may be made of the method in which a solution of asynthetic polymer containing a blowing agent is applied to a base fabricand then the blowing agent is allowed to form by heating or some othermeans to thereby form a porous layer of the synthetic polymer. Accordingto this method, however, the pores thereby formed are spherical orelliptic, large in diameter and consist predominantly of independentpores, so it is difficult to attain a sufficient air- and moisturepermeability though water-proofness is obtained.

OBJECT OF THE INVENTION

It is the object of this invention to provide a coated fabric whichremedies the above-mentioned drawbacks and which has superior moisturepermeability and water-proofness.

DETAILED DESCRIPTION OF THE INVENTION

According to this invention, in the so-called wet coagulation methodwherein a microporous polyurethane layer is formed on a base fabric,there is used as a coating solution a polar organic solvent solutioncontaining 8 to 25% by weight of a polyurethane elastomer, 0.1 to 10% byweight of a water repellent agent which, with respect to apolyisocyanate used, is stable at a temperature not higher than 40° C.and can react at a temperature not lower than 100° C., 0.2 to 3% byweight of the polyisocyanate and 1 to 8% by weight of a nonionicsurfactant, whereby the fine pores present within a microporouspolyurethane layer formed by wet coagulation of the said coatingsolution are adjusted in diameter to not larger than 5 microns and atthe same time a durable water repellency is imparted to the surfaces ofsuch fine pores. In this way, a coated fabric having superior moisturepermeability and water proofness is obtained.

The term "fabric" as used herein means a general term for fabricatedmaterials including woven fabric, knitted fabric, non-woven fabric andthe like.

As water repellent agent to be incorporated into the coating solution ofthe invention, there may be used any water repellent agent if only, withrespect to a polyisocyanate used, it is stable at a low temperature,e.g. not higher than 40° C., and can react at a high temperature, e.g.not lower than 100° C. When such a water repellent agent is usedtogether with polyisocyanates, it is made possible to impart a durablewater repellency not only to the surface of a microporous polyurethanelayer formed by the wet coagulation method, but also to the surfaces ofmany fine pores, namely inner wall portions of the pores, present withinthe said layer. If a water repellent agent used reacts at a lowtemperature with a polyisocyanate used, the coating solution whichcontain them becomes gelled and unemployable. In contrast therewith, ifthe two react at a high temperature, the bonding property between thewater repellent agent and the microporous polyurethane layer (includingthe surfaces of fine pores present within the said layer) is enhancedand an excellent, durable water-proofness can thereby be attained. Ingeneral, fluorine- and silicone-based water repellent agents availablecommercially are preferable. For example, dimethylpolysiloxane,methylhydrogenpolysiloxane, ##STR1## (x is H or F, m is an integer of1-20 and n is a degree of polymerization) are exemplified. Among all,fluorine-based water repellent agents are more effective. It is alsoeffective to use both fluorine- and silicone-based water repellentagents.

If the content of a water repellent agent is smaller than 0.1% byweight, a sufficient water repellency will not be obtained, while acontent thereof larger than 10.0% by weight tends to make non-uniformthe size of pores present within a microporous layer formed by wetcoagulation. In the case of fluorine-based water repellent agent, it ispreferable that the mixing ratio thereof in a treating bath be in therange of from 0.1 to 1.0% by weight, and this range is preferred formaking the pores uniform.

By way of illustrating the polyisocyanate to be used together with awater repellent agent, mention may be made of an organic compound havingtwo or more isocyanate groups such as di- or triisocyanate. For example,it may be selected optionally from diisocyanates such as2,4-(2,6-)tolylene diisocyanate, diphenylmethane 4,4'-diisocyanate,1,4-naphthalene diisocyanate, isophorone diisocyanate, and hexamethylenediisocyanate, and triisocyanates resulting from the addition reaction of3 moles of these diisocyanates and 1 mole of active hydrogen-containingcompounds such as trimethylolpropane and glycerin. These polyisocyanatesmay have their isocyanate groups in a free form or in a stabilized formwith added phenol, etc.

The simultaneous use of polyisocyanate is effective in enhancing thebonding property of a water repellent agent to a microporouspolyurethane layer and imparting durability to the water repellency asreferred to previously, and also effective in improving thecrease-flex-resistance of the microporous layer. If the content of apolyisocyanate is lower than 0.2% by weight, the polyisocyanate will notexhibit its function and effect to a satisfactory extent, resulting inthe durability of the water repellency and the crease-flex-resistance ofthe microporous layer becoming insufficient. On the other hand, with ahigher content thereof than 3.0% by weight, the handling or the feelingof the resulting coated fabric becomes coarse and hard though thebonding effect is remarkable.

As a nonionic surfactant to be used in this invention there may be usedany nonionic surfactants available commercially, but especially anonionic surfactant consisting of a block copolymer of polypropyleneglycol and polyethylene glycol affords good results.

The use of such a nonionic surfactant in this invention is effective inenhancing the compatibility of the foregoing water repellent agent andpolyisocyanates and, if any, pigments and other additives, with thepolyurethane solution, and also effective in adjusting, when thepolyurethane solution is immersed in coagulating bath, the disolvingspeed of the solvent in the polyurethane solution into the coagulatingbath, as well as the permeating and diffusing speed of water in thecoagulating bath into the polymer solution, resulting in that not onlythe pores present within the formed microporous layer are made uniformand fine, but also the bulk of the water repellent agent can beconcentrated uniformly on the pore surfaces and the partition wallsurface between pores. If the content of a nonionic surfactant is lowerthan 1% by weight, the function and effect of the surfactant will beunsatisfactory, while with a higher content thereof than 8% by weight,the pores present within the resulting microporous layer tend to becomecoarse; besides, the water repellent agent used tends to flow into thecoagulating bath without staying on the pore surfaces.

The viscosity of the aforesaid coating solution used in this inventionis not specially limited, but an extremely low viscosity thereof wouldmake it difficult to suppress the permeation of the said solution into abase fabric even if a pre-treatment is applied; therefore, suchviscosity should be taken into account together with the method ofpre-treatment.

In this invention, as will be apparent from the foregoing description, apolyurethane elastomer solution is used as a coating solution whichcontains a water repellent agent, a polyisocyanate and a nonionicsurfactant in the respective amounts within predetermined ranges toallow these components to exhibit a synergistic effect whereby a largenumber of fine pores present within a microporous layer formed by wetcoagulation are adjusted to 5 microns or less in diameter and a durablewater repellency is imparted even to the surfaces of such pores, andthus a coated fabric having an excellent durable water-proofness and ahigh moisture permeability can be obtained easily.

Therefore, it goes without saying that a commonly used means in theso-called wet coagulation method may be adopted optionally as long as itdoes not impede the function and effect of the above-mentionedcomponents of the coating solution. But it is desirable that theconcentration of polyurethane elastomer in the coating solution be inthe range of from 8 to 25% by weight. In more particular terms, as apolyurethane elastomer to be used as a coating solution there may beused a polyester type polyurethane elastomer or a polyether typepolyurethane elastomer, but in the formation of a microporouspolyurethane layer according to the wet coagulation method theregenerally exists a correlation between the concentration of polyurethaneelastomer and the diameter of pores present within the microporouslayer; that is, as the said concentration becomes lower the porediameter tends to become larger, while as it becomes higher the poresshow a tendency to a smaller diameter. In this invention, suchtendencies are mitigated by the function and effect of a nonionicsurfactant contained in the coating solution, but if the concentrationof polyurethane elastomer is lower than 8% by weight, it is difficult toadjust the pores within the microporous layer to not larger than 5microns in diameter, while if the concentration thereof is higher than25% by weight the moisture permeability, one of the objects of theinvention, is difficult to attain and the handling of the resultingcoated fabric becomes rubber-like, though very fine pores can be formed.A polar organic solvent to be used in this invention is not speciallylimited. Dimethylformamide, dimethylacetamide, dimethylsulfoxide areexemplified.

A coagulating bath to be used in this invention is not speciallylimited, but it is advantageous to use an aqueous solution containing 5to 20% by weight of a polar organic solvent such as dimethylformamide.

The foregoing coating solution is applied uniformly in a desiredthickness using a knife-over-roll coater or other conventional coatingmachine.

In this invention, the foregoing polar organic solvent solution as acoating solution containing polyurethane may be directly applied to atleast one face of a base fabric followed by application of a coagulationtreatment, but it is desirable to apply a pre-treatment with a view toimproving the moisture permeability, the handling of the resultingcoated fabric and the bonding property between the microporous layer andthe base fabric. In such a pre-treatment process, it is desirable inpoint of handling and moisture permeability that polyurethane be allowedto permeate in the direction of the thickness of the base fabric and upto about one-third of the same thickness, but a further permeation notallowed.

To be concrete, the face of a base fabric to which is to be applied apolyurethane solution is heated and pressurized by calendering or someother suitable means to allow fibers to be transformed in section so asto become more narrowly spaced from each other, or a silicone- orfluorine-based water repellent agent may be applied to the base fabric.By applying such treating means to a base fabric as necessary, not onlythe permeation of a polyurethane solution into the base fabric can besuppressed but also the bonding between the fibers constituting the basefabric and the synthetic polymer is relaxed when applying the saidpolymer solution to the base fabric, so that there is obtained a coatedfabric of a drape handling having superior moisture- and airpermeability and a high peeling strength. In this case, if thepolyurethane solution permeates in the direction of the thickness of thebase fabric more than one-third of the said thickness, moisturepermeability, tearing strength and other physical properties anddrapeness are lowered.

As a water repellent agent to be used in the aforesaid pre-treatingprocess, the use of a conventional silicone-based repellent agentaffords almost the same function and effect as in the use of afluorine-based water repellent agent, but would result in decrease inthe peeling strength between polymer layer and base fabric and thedurability being insufficient, so the use of a fluorine-based waterrepellent agent is preferred. The amount of a fluorine-based waterrepellent agent to be adhered to a base fabric is desirably in the rangeof from 0.03 to 1.0% by weight though it is connected with the viscosityof the polymer solution used in the following step. Outside this range,for example in the case of the adhesion amount being smaller than 0.03%by weight, the permeation of the polyurethane solution into a basefabric will become less suppressible and consequently the resultingcoated fabric is deteriorated in drapeness of its handling and inmoisture permeability. On the other hand, with an adhesion amount largerthan 1.0% by weight, the effect of the treatment in question isremarkable and the resulting coated fabric has a very drape handling andan excellent moisture permeability, but the peeling strength anddurability are poor.

If to the base fabric thus subjected to the water repellent treatment isfurther incorporated not more than 100% by weight, based on the weightof the base fabric, of water or a mixed solution of water and a polarorganic solvent and thereafter the foregoing application process iscarried out, the resulting function and effect are remarkable ascompared with the only water repellent treatment case and particularlythe peeling strength is improved to a large extent, though the mechanismof action is not fully known.

In this invention, moreover, it is desirable to include the followingstep in the pre-treatment in order to improve the moisture permeabilityand water-proofness and to remedy the drawback incidental to a coatedfabric that it is coarse and hard and is less durable. Such additionalstep just referred to above is a step wherein to the surface of a basefabric to which is to be applied to polyurethane is applied a syntheticpolymer of a different composition from the polyurethane, especially asynthetic polymer having a bonding function, in dotted or intermittentlylinear form. That is, before applying a polyurethane coating solution toa base fabric, a polymer of a different composition from thepolyurethane is applied to the base fabric in dotted form orintermittently, thereafter a polar organic solvent solution consistingessentially of polyurethane is applied to the base fabric and then thelatter is immersed in a coagulating bath to form a microporouspolyurethane layer having moisture permeability. Applying such asynthetic polymer in dotted form or intermittently is advantageous inthat the permeation of polyurethane into a base fabric can be easilysuppressed to one-third or less of the thickness of the base fabric andin that the moisture permeability and handling are less damaged sincethe said synthetic polymer is applied in dotted or intermittent form.Furthermore, since the moisture-permeable microporous layer consistingessentially of polyurethane and the base fabric are bonded togetherthrough the medium of the synthetic polymer applied in dotted orintermittent form, the peeling strength can be remarkably improvedwithout spoilage of handling of the fabric. The thickness of a basefabric as referred to herein means a substantial thickness of the basefabric, which is measured with a thickness meter except naps and fluffsif any.

In this invention, to apply synthetic polymer of a different compositionfrom polyurethane there may be used a known method such as a dottedcoating roller or spray system. On the other hand, for applying suchsynthetic polymer in an intermittent manner there may be adopted variousarranging methods, for example, a parallely arranged form of plurallinear matters, a crossed arrangement of plural linear matters in theform of a rhomb or checkers, or a piled arrangement of linear matters inthe form of a meandering or spiral.

As a synthetic polymer to be applied in dotted or intermittent form to abase fabric, there may be employed any known synthetic polymers if onlythey have an adhesive force and per se are insoluble or difficult todissolve in polar organic solvents, or become insoluble or difficult todissolve in polar organic solvents in combination thereof with anadhesive (cross-linking agent). Acrylic polymers are typical examples ofsuch synthetic polymer. It is desirable that such synthetic polymer beapplied to a base fabric in an area of 20 to 80% of the surface of thebase fabric. If the applied area is smaller than 20%, the effect ofsuppressing the permeation of the polyurethane solution into a basefabric is poor, and the effect of enhancing the peeling strength betweenthe formed microporous polyurethane layer and the base fabric is alsopoor. On the other hand, with an applied area exceeding 80%, the effectof suppressing the permeation of the polyurethane soluton into a basesubstrate is outstanding and the peeling strength is enhanced to aremarkable extent, but the moisture permeability of the resulting coatedfabric is lowered to a large extent and the handling thereof becomescoarse and hard.

In this invention, the peeling strength referred to above can be changedfreely by adjusting and selecting the kind, applied amount and appliedspacing of such synthetic polymer. It is desirable that the peelingstrength be as high as possible, but the range of the peeling strengthis limited of itself in balance with the drapeness of handling andmoisture permeability. Peeling strengths lower than 100 g/cm are notpreferred, because with such values the coated fabrics concerned are ofno utility and the moisture permeable layer comes off soon in ordinaryuse. In this invention, therefore, a base fabric is treated so that thepeeling strength is not lower than 100 g/cm, preferably not lower than200 g/cm. It goes without saying that the aforesaid processing step maybe carried out in combination with the foregoing pre-treatment.

By way of illustrating base fabrics used in this invention, mention maybe made of woven, knitted and non-woven fabrics, and the fibersconstituting those fabrics may be any of natural fibers such as cotton,silk and wool, chemical fabrics such as cellulose, viscose rayon andcupra, and synthetic fibers such as polyamide, polyester and polyacrylicsynthetic fibers; furthermore, they may be filament yarn, spun yarn,blended spun yarn, or mixed fabric thereof. In the case of a fabric madeof staple fibers, however, it is desirable that, before or intermediateof the treatment of the invention, fluffs be decreased by calendering,fluff singeing, or like means.

In this invention, a base fabric which has been subjected to theforegoing coagulation treatment may be further subjected to anotherwater repellent treatment. This additional step is not essential, butmay be applied as necessary whereby a more permanent water repellencycan be imparted to the surface of the formed microporous layer.

As the water repellent agent used in the invention, there may beemployed any conventional water repellent agents, including fluorine-and silicon-based ones. The amount of water repellent agent adhered to abase fabric may vary according to the use, but generally it is in therange of from 0.5 to 2.0% by weight.

The fabric which has been treated as herein defined may be furthersubjected to known treatments as necessary such as curing, tentering andsoftening.

Any fabrics from thin to voluminous ones can be treated according tothis invention. Furthermore, fabric in multilayered form is alsoemployable.

An example of method of making a coated fabric according to thisinvention has been described above, and in this connection we have foundthat in the wet coagulation method using the same polyurethaneelastomer, even if the composition of the treating bath is somewhatchanged, there is obtained a coated fabric having the same performance.In more particular terms, there is used a coating solution prepared byadding and mixing a metal complex of the formula shown below into apolyurethane elastomer and dissolving and dispersing the mixture in apolar organic solvent such as dimethylformamide. The content of themetal complex is preferably 1 to 10% by weight. Of course, to thiscoating solution there may be added and mixed as necessary a waterrepellent agent such as a silicone- or fluorine-based water repellentagent, a nonionic surfactant, or diisocyanate, or further an inorganicparticulate matter. Also, it goes without saying that the foregoing pre-and after-treatment steps may be applied as necessary to a base fabric:##STR2## wherein R is a hydrocarbon radical having 8 or more carbonatoms, M is Cr or Al, and A is Cl or OH. Preferable R is an alkylradical having 8 to 20 carbon atoms such as decyl, hexadecyl, octadecyl.

The following description is now provided about the structure andcharacteristic of a coated fabric obtained according to this invention.The coated fabric is represented as a moisture-permeable waterproofcoated fabric having on at least one face thereof a microporous layer ofa synthetic polymer consisting essentially of polyurethane,characterized by having a water entry pressure not lower than 700 mmH₂O/cm², a moisture permeability not lower than 2500 g/m² ·24 hrs,preferably not lower than 5000 g/m² ·24 hours, and an air permeability(measured by the Gurley method) not higher than 600 sec/100 cc.

The moisture-permeable waterproof coated fabric of this invention isfurther characterized in that the crease-flex-resistance of themicroporous layer formed of the foregoing synthetic polymer is 200times/1 kg load or higher, the impregnation degree of the said layerinto a base fabric is one-third or less of the thickness of the basefabric, and the peeling strength is 100 g/cm or higher.

According to this invention, moreover, an outstanding effect isexhibited by the structure that the microporous layer formed of asynthetic polymer consisting essentially of polyurethane has a multitudeof fine pores in its surface and relatively large cavity portionscommunicating with the said fine pores are formed inside the layer, andfurther a communication hole is formed at least in part of the partitionwall between adjacent said cavity portions. An outstanding effect isattained particularly when the diameter of the surface fine pores is notlarger than 5 microns, preferably not larger than 3 microns and morepreferably not larger than 1 micron, and the diameter of the cavityportion is at least three times the diameter of the fine pores.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention will be described by way of examplewith reference to the accompanying drawings. In said drawings:

FIG. 1 is an enlarged sectional view of a coated layer formed accordingto this invention;

FIG. 2 is an enlarged sectional view showing an example of a fabricwhich has been subjected to a process for improving peeling strength andfor imparting drapeness;

FIG. 3 is a microphotograph showing the section of coated fabric whichserved as the base of the layer shown in FIG. 1;

FIG. 4 is a microphotograph of the coated surface of the coated fabricmade according to this invention.

A microporous layer 1 is formed on the surface of a base fabric 2, whileinside the microporous layer are formed a multitude of cavity portions4, 4', 4" having very small inside diameters. On the other hand, in themicroporous layer 1 are formed a large number of fine pores 3, 3', 3"most of which are not larger than 5 microns in diameter and among whichthere exist many whose diameters are not larger than 1 micron. An actualmeasurement for the product made according to a working example of theinvention showed that the diameters of the fine pores were distributedfrom 0.1 to 3.0 microns and that fine pores of 0.1 to 1.0 micronsoccupied a considerable proportion. Most of these fine pores communicatewith the cavity portions 4, 4', 4" formed inside the microporous layer,the diameters of the void portions of the said cavity portions being atleast three times the diameters of the fine pores, and consequently theso-called bottle shape is formed, which structure has never been thoughtof heretofore. It is preferable that an average diameter of the voidportion be usually 50 microns and especially up to about 30 microns. Inthe cavity portion 4' shown in FIG. 1, the X and Y of the void portionwere measued to find that X was 20 microns and Y 12 microns.

In this invention, moreover, one or more fine holes 5, 5', 5" are formedin part or the whole of the partition wall between adjacent cavityportions whereby the cavity portions are communicated with each other.Such communication holes have a diameter not larger than 5 microns,usually about 0.1 to about 3 microns. Conventional microporous layersare of a structure such that a large number of independent air bubblesare formed therein, or of a structure such that tubular holes exist inlarge numbers which communicate between the surface and the back;besides, their diameters are mostly not smaller than 10 microns, so thatthe resulting coated fabric is inferior in moisture- and airpermeability or inferior in water-proofness. On the other hand, the oneformed according to this invention is a new microporous layer comprisingthe combination of very fine pores of not larger than 5 microns indiameter and relatively large cavity portions, so that it is possible toobtain a coated fabric superior in water resistance, drapeness, peelingstrength and also superior in moisture- and air permeability,water-proofness. Since the microporous layer formed according to thisinvention has such a characteristic feature as mentioned above, it canexhibit superior functions in point of water-proofness and moisturepermeability. The fine pores formed in the surface of the microporouslayer of the invention are existent in extremely large numbers. Forexample, as a result of checking such fine pores with respect to acertain limited portion, it was found that more than half a millionpores were existent per square centimeter. In this invention, themicroporous layer of the structure shown in FIG. 1 and FIG. 3 isexistent at a fairly large probability throughout the resulting coatedfabric.

FIG. 2 is an enlarged sectional view showing an example of a fabricwhich has been subjected to a processing for improving peeling strengthand for imparting drapeness, in which an adhesive polymer 6 is arrangedin spaced, dotted form between the base fabric 2 and the microporouslayer 1. The microporous layer 1 illustrated in FIG. 2 and FIG. 4 is ofthe same structure as the microporous layer shown in FIG. 1.

The moisture-permeable waterproof coated fabric of this invention hassuperior water-proofness and moisture permeability and a moderate airpermeability and further durability without spoilage of its handling,and these characteristics permit it to be used in a wide variety ofapplications, including sports wears such as golf wear, jackets, windbreaker and ski wear, cold-proof cloths, rain wears, work clothes,tents, canvas shoes and diaper covers.

EXAMPLES

Working examples of this invention are given below to further illustratethe invention. All the parts shown in the examples are by weight.

EXAMPLE 1

15 parts of a polyester type polyurethane elastomer, 5 parts of afluorine-based repellent agent, 0.8 part of atrimethylolpropane-hexamethylene diisocyanate adduct and 5 parts of apolypropylene glycol-polyethylene glycol block copolymer (a nonionicsurfactant) were dissolved in 74.2 parts of dimethylformamide to preparea coating solution. The coating solution thus prepared was applied ontoa pre-softened nylon taffeta in an amount of about 300 g/m² by means ofa reverse roll coater. Immediately thereafter, the nylon taffeta wasconducted into an aqueous solution containing 10% by weight ofdimethylformamide and immersed therein for 5 minutes at 20° C. to allowgelation to take place, then washed with hot water at 80° C. for 30minutes and, after hot air drying at 120° C., it was heat-treated at140° C., whereby a coated fabric of drape handling was obtained.

The coated fabric was immersed in a silicone emulsion at a concentrationof 3% by weight, then squeezed by a mangle uniformly at a squeeze ratioof 50% and thereafter heat-treated at 150° C. for 30 seconds by aconventional heat setter.

The resulting product possessed superior water-proofness and moisturepermeability, having a water entry pressure of 1600 mmH₂ O/cm², a waterrepellency of 100 and a moisture-vapor transmission of 2500 g/m² ·24hrs, and its resistance to washing and to dry cleaning was good, so itwas suitable for such uses as skiing anorak and rain wears.

On the other hand, using as a coating solution a dimethylformamidesolution containing 15% by weight of a polyester type polyurethaneelastomer, a base fabric was subjected to application of the coatingsolution, wet coagulation, hot water washing and drying in the samemanner as in Example 1 to give a coated fabric. The coated fabric wasimmersed in an aqueous dispersion containing 5% by weight of afluorine-based water repellent agent, then squeezed by a mangle at asqueeze ratio of 50% and thereafter heat-treated at 150° C. for 30seconds by a heat setter. The resulting product was inferior indrapeness to the foregoing product obtained according to the method ofthis invention. Also in physical properties it was insufficient in pointof water-proofness (particularly water entry pressure) and moisturepermeability, having a water entry pressure of 210 mmH₂ O/cm², a waterrepellency of 90 and 100 and a moisture-vapor transmission of 1300 g/m²·24 hrs. Thus, the use thereof as a waterproof clothing wasinappropriate.

(Note) The physical properties were measured according to the followingmethods:

Water entry pressure JIS L-1079

Water repellency JIS L-1079

Moisture-vapor transmission JIS Z-0208

EXAMPLE 2

20 parts of a polyester type polyurethane elasomer, 4 parts each offluorine- and silicone-based water repellent agents, 2 parts ofisophorone diisocyanate and 4 parts of a polypropyleneglycol-polyethylene glycol block copolymer were dissolved in 66 parts ofdimethylformamide to prepare a coating solution.

The coating solution thus prepared was applied onto a polyester twillfabric in an amount of about 200 g/m² by means of a knife-over-rollcoater, then conducted into an aqueous dimethylformamide solution at aconcentration of 5% by weight and immersed therein for 5 minutes at 30°C. to allow gelation to take place and, after hot air drying at 120° C.,it was heat-treated at 140° C. for 5 minutes.

The resulting coated fabric possessed a moderate drapeness and superiorwater-proofness and moisture permeability, having a water entry pressureof 2000 mmH₂ O/cm², a water repellency of 100 and a moisture-vaportransmission of 2500 g/m² ·24 hrs. These physical properties were littledeteriorated even after washing five times in accordance with JIS L-0844(A-2). Thus, this coated fabric was suitable for various waterproofcloths.

On the other hand, using the same recipe as that in Example 2 exceptthat two parts of isophorone diisocyanate was not used, a base fabricwas treated in the same manner as in Example 2 to give a drape coatedfabric. This coated fabric possessed about the same physical propertiesas those of the coated fabric obtained in Example 2, but on washing itswater-proofness deteriorated to a remarkable extent; water entrypressure 500 mmH₂ O/cm², water repellency 50. Thus, this coated fabricwas unsuitable for practical use.

EXAMPLE 3

A nylon woven fabric having stretchability was immersed in 100 parts ofan aqueous dispersion containing 3 parts of a fluorine-based waterrepellent agent, then squeezed by a mangle at a squeeze ratio of 40% andthereafter heat-treated at 150° C. for 30 seconds by a heat setter.

Separately, coating solution was prepared by dissolving 15 parts of apolyether type polyurethane elastomer, 5 parts of a fluorine-based waterrepellent agent, 2 parts of a trimethylolpropanehexamethylenediisocyanate adduct and 2 parts of a nonionic surfactant, in 76 parts ofdimethylformamide. The coating solution thus prepared was applied ontothe above base fabric subjected to the water repellent treatment in anamount of about 70 g/m² using the gravure printing method. Immediatelythereafter, the base fabric was conducted into water and immersedtherein for 5 minutes to allow gelation to take place, then dried withhot air at 120° C. and thereafter heat-treated at 140° C. for 5 minutes.

The resulting coated fabric was very soft and drape, possessing superiormoisture permeability and water-proofness; water entry pressure 800 mmH₂O/cm², water repellency 100, moisture-vapor transmission 3800 g/m² ·24hrs. Besides, these physical properties were resistant to washing withlittle deterioration recognized even after washing five times. Thus,this coated fabric was suitable for sports wears.

EXAMPLE 4

A fabric made of a blended polyester-cotton spun yarn was treated with asolution of a fluorine-based water repellent agent, then dried andheat-treated. The amount of the water repellent agent adhered to thefabric was 0.04% by weight.

Separately, a coating solution (viscosity 900 cps at 30° C.) wasprepared by dissolving 15 parts of a polyester type polyurethaneelastomer, 0.4 part of a fluorine-based water repellent agent, 1.0 partof a trimethylolpropane-hexamethylene diisocyanate (molar ratio 1:3)adduct and 5 parts of a polypropylene glycol-polyethylene glycol blockcopolymer (a nonionic surfactant), in 78.6 parts of dimethylformamide.The coating solution thus prepared was applied onto the above basefabric subjected to the water repellent treatment in an amount of about300 g/m² (wet) using a reverse roll coater. Then, the base fabric wasimmersed in an aqueous solution containing 10% by weight ofdimethylformamide at 30° C. for 5 minutes to allow gelation to takeplace, washed with hot water at 80° C. for 30 minutes, dried with hotair and thereafter heat-treated at 140° C. for 3 minutes.

The resulting coated fabric was immersed in a solution containing 1% byweight of a fluorine-based water repellent agent, then squeezed by amangle uniformly at a squeeze ratio of 70% and thereafter heat-treatedat 150° C. for 30 seconds using a heat setter.

The product thus obtained, with the polyurethane coating solution littleimpregnated in the interior of the base fabric, possessed superiorwater-proofness and moisture permeability; water entry pressure 1600mmH₂ O/cm², moisture-vapor transmission 5500 g/m² ·24 hrs, airpermeability 90 sec/100 cc, peeling strength 400 g/cm,crease-flex-resistance 5000 times/1 kg load. Besides, its resistance towashing was very high with little change recognized in physicalproperties even after washing five times. Coupled with a drape handling,this product was suitable for such uses as skiing anorak and othersports wears and rain wears.

Separately, after treating the fabric with the fluorine-based waterrepellent agent in the above Example 4, the fabric was furtherimpregnated with 70% by weight of a mixed dimethylformamide/water(30/70) solution and then treated in the same manner as in Example 4 togive a coated fabric of drape handling. The peeling strength 700 g/cm ofthis product is a further improvement from that of the product obtainedin Example 4, the other physical properties being the same as thoseattained in Example 4. The product was a coated fabric having bothmoisture permeability and water-proofness superior in durability. It wassuitable for such applications as tents and other materials in additionto sports and rain wears.

On the other hand, a coated fabric was obtained in the same manner as inExample 4 except that the base fabric was not treated with thefluorine-based water repellent agent and as a coating solution there wasused a dimethylformamide solution containing 15% by weight of only thepolyester type polyurethane elastomer used in Example 4. In this coatedfabric, the polyurethane coating solution permeated the interior of thebase fabric with a portion thereof permeated as far as the opposite faceto the applied face, and consequently the handling of this coated fabricbecame coarse and hard as compared with the product obtained in Example4 according to the method of this invention. Also in physicalproperties, which were water entry pressure 1800 mmH₂ O/cm²,moisture-vapor transmission 700 g/m² ·24 hrs, air permeability 700sec/100 cc and crease-flex-resistance 1000 to 200 times/1 kg load, thisproduct was inferior in air- and moisture permeability and inresistance-to-flex-cracking, though it possessed water-proofness. Thus,this product was unsuitable for the clothing use.

(Note) The physical properties were measured according to the followingmethods:

Water entry pressure JIS L-1079 (ASTM D751)

Moisture-vapor transmission JIS Z-0208 (ASTM E96-66)

Air permeability JIS L-1006 (FED STD5452)

Peeling strength JIS K-6328 (ASTM D-751)

Crease-flex-resistance JIS K-6328 (ASTM D-751)

Washing resistance JIS L-0844 (A-2)(AATCC36-1969-Test 2)

EXAMPLE 5

A polyester twill fabric was immersed in an aqueous dispersioncontaining 2% by weight of a fluorine-based water repellent agent, thensqueezed by a mangle uniformly at a squeeze ratio of 40% and thereafterheat-treated at 150° C. for 30 seconds using a heat setter.

Separately, a coating solution (viscosity 1500 cps at 30° C.) wasprepared by dissolving or dispersing 20 parts of a polyether typepolyurethane elastomer, 0.8 part of a fluorine-based water repellentagent, 2 parts of isophorone diisocyanate, 4 parts of a polypropyleneglycol-polyethylene glycol block copolymer and 5 parts of silica gel, in68.2 parts of dimethylformamide. The coating solution thus prepared wasapplied onto the above base fabric subjected to the water repellenttreatment in an amount of about 200 g/m² (wet) using a knife-over-rollcoater. The base fabric was then conducted into an aqueous solutioncontaining 5% by weight of dimethylformamide and immersed therein for 5minutes at 30° C. to allow gelation to take place, dried with hot air at120° C. and heat-treated at 140° C. for 5 minutes.

The resulting coated fabric, with little permeation of the polyurethanecoating solution in the interior of the base fabric, possessed a drapehandling and superior water-proofness and moisture permeability; waterentry pressure 2000 mmH₂ O/cm², moisture permeability 5100 g/m² ·24 hrs.The peeling strength and the crease-flex-resistance were also high, 350g/cm and 3000 times/1 kg load, respectively. These physical propertieswere little deteriorated even after washing five times. Thus, thisproduct was suitable for various waterproof cloths. In the microporouslayer were formed pores of 1 micron and cavity portions of 15 micronsboth on the average in diameter, with the cavity portions communicatedwith the surface pores through fine holes formed in the wall portionsthereof.

EXAMPLE 6

A nylon taffeta fabric was treated with a fluorine-based water repellentagent. The amount of the water repellent agent adhered to the taffetawas 2% by weight.

20 parts of a polyester type polyurethane elastomer, 0.5 part by weightof fluorine-based water repellent agent, 2 parts of isophoronediisocyanate and 5 parts of a polypropylene glycol-polyethylene glycolblock copolymer were dissolved in 72.5 parts of dimethylformamide toprepare a coating solution (viscosity 1600 cps at 30° C.). The coatingsolution thus prepared was applied onto the above taffeta subjected tothe water repellent treatment in an amount of about 300 g/m² (wet) usinga knife-over-roll coater.

A nylon half tricot fabric which had been treated with a fluorine-basedwater repellent agent (the amount of the water repellent agent adheredto the tricot being 0.05% by weight) was sticked in load- andtension-free state to the surface of the taffeta to which had beenapplied the foregoing polyurethane coating solution. Then, the stickedmass was immersed in an aqueous bath containing 10% by weight ofdimethylformamide, was allowed to become gelled at 30° C. for 10minutes, washed with hot water at 80° C. for 30 minutes, dried with hotair and thereafter the nylon taffeta was separated.

By applying the above-mentioned treatment, there was obtained a coatedfabric with a microporous polyurethane layer formed on the surface ofthe nylon half tricot.

This coated fabric, with little permeation of the polyurethane coatingsolution in the interior of the base fabric, preserved the elasticityand drapeness of the tricot itself and possessed excellent physicalproperties superior in both water-proofness and moisture permeability;peeling strength 250 g/cm, water entry pressure 1500 mmH₂ O/cm²,moisture-vapor transmission 6000 g/m² ·24 hrs, air permeability 3sec/100 cc, crease-flex-resistance 5000 times or more/1 kg load.Furthermore, the microporous layer was of the structure as thoseobtained in Example 1 and illustrated in FIG. 1.

EXAMPLE 7

Onto a nylon taffeta (warp and weft of 70 denier nylon filament yarn,warp density×weft density=123×87) was partially printed and applied atoluen solution (viscosity 2000 cps at 20° C.) containing 15% by weightof an acrylic ester copolymer and 3% by weight of atrimethylolpropane-hexamethylene diisocyanate (molar ratio 1:3) adduct,by means of an engraved roller with multiple dots of 87 microns in depthand with a printing area of 50%, followed by drying and heat treatment.The amount of the said copolymer adhered to the base fabric was 10 g/m²(wet).

Onto the base fabric treated as above was further applied adimethylformamide solution (viscosity 8000 cps at 20° C.) containing 20%by weight of polyurethane and 4% by weight of a pore controller in anamount of 150 g/m² (wet) by means of a knife-over-roll coater. Then, thebase fabric was immersed in a water bath, allowed to coagulate, washedwith water, dried and thereafter heat-treated at 150° C. for 10 minutes.The characteristics of the resulting moisture-permeable coated fabricare shown in Table 1.

By way of comparison, Table 1 also shows the characteristics of a coatedfabric obtained according to this working example but to which was notapplied at all the acrylic ester copolymer solution, and also thecharacteristics of a coated fabric obtained according to this workingexample but in which the said polymer solution was applied to the entiresurface of the base fabric using the knife-over-roll coater.

                                      TABLE 1                                     __________________________________________________________________________              Moisture-permeable                                                            coated fabric                                                                 according to this                                                                       Comparative                                                                           Comparative                                                 invention Example Example                                           __________________________________________________________________________    Application state                                                                       Applied in multi-                                                                       Not applied                                                                           Applied to the                                    and amount (g/m.sup.2)                                                                  ple dots form     entire surface                                    of acrylic ester                                                                        10 (wet)          50 (wet)                                          copolymer                                                                     Permeation of                                                                            25       A portion                                                                              0                                                polyurethane into   permeated the                                                                         But a portion of                                  base fabric         reverse side                                                                          acrylic ester                                     (%/base fabric      of base fabric                                                                        copolymer permeat-                                thickness)                  ed the reverse                                                                side of base                                                                  fabric                                            Moisture-vapor                                                                          4100      2400    800                                               transmission                                                                  (cc/m.sup.2 · 24 hrs)                                                Peeling strength                                                                        400        90     600                                               (g/cm)                                                                        Handling  Very drape                                                                              A little                                                                              Coarse and hard                                                       inferior                                                  __________________________________________________________________________     (Note)                                                                        Moisturevapor transmission JIS Z0208                                          Peeling strength JIS K6328                                               

EXAMPLE 8

12 parts of a polyether type polyurethane elasomer, 1 part of afluorine-based water repellent agent, 0.5 part of atrimethylolpropane-2,4-tolylene diisocyanate adduct, 1 part of apolypropylene glycol-polyethylene glycol block copolymer and 3 parts ofa finely-powdered silica gel were dissolved and dispersed in 82.5 partsof dimethylformamide to prepare a coating solution.

The coating solution thus prepared was applied to a fabric made of ablended nylon-cotton spun yarn in an amount of about 150 g/m² using aknife-over-roll coater. The base fabric was conducted into a 10% byweight aqueous dimethylformamide solution and immersed therein for 5minutes at 30° C. to allow gelation to take place, then dried with hotair at 120° C. and thereafter heat-treated at 140° C. for 5 minutes.

The coated fabric thus obtained was immersed in a solution of afluorine-based water repellent agent at a concentration of 2% by weight,then squeezed by a mangle uniformly at a squeeze ratio of 50% andthereafter heat-treated at 150° C. for 30 seconds by a conventional heatsetter.

The resulting product possessed superior water-proofness and moisturepermeability, having a water entry pressure of 1400 mmH₂ O/cm², waterrepellency of 100 and a moisture-vapor transmission of 5100 g/m² ·24hrs. Besides, these physical properties were little deteriorated evenafter washing five times. Thus, this product was suitable for variouswaterproof clothes.

EXAMPLE 9

A fabric made of a blended polyamide-cotton spun yarn was immersed in anaqueous dispersion containing 2% by weight of a fluorine-based waterrepellent agent, then squeezed by a mangle uniformly at a squeeze ratioof 40% and thereafter heat-treated at 150° C. for 30 seconds using aheat setter.

Separately, a coating solution (viscosity 1300 cps at 30° C. ) wasprepared by dissolving and dispersing 15 parts of a polyester typepolyurethane elastomer, 1.0 part of a fluorine-based water repellentagent, 2 parts of a silicone-based water repellent agent, 1.0 part of atrimethylolpropanehexamethylene diisocyanate (molar ratio 1:3) adductand 5 parts of a polypropylene glycol-polyethylene block copolymer, in81 parts of dimethylformamide. The coating solution thus prepared wasapplied to the above base fabric subjected to the water repellenttreatment in an amount of about 200 g/m² (wet) using a knife-over-rollcoater. The base fabric was then conducted into an aqueous solutioncontaining 10% by weight of dimethylformamide and immersed therein for 5minutes at 30° C. to allow gelation to take place, dried with hot air at120° C. and heat-treated at 140° C. for 5 minutes.

The coated fabric thus obtained was immersed in a solution containing 1%by weight of a fluorine-based water repellent agent, then squeezed by amangle uniformly at a squeeze ratio of 50% and thereafter heat-treatedat 150° C. for 30 seconds using a heat setter.

The resulting product, with little permeation of the polyurethanecoating solution in the interior of the base fabric, possessed a drapetexture and superior water-proofness and moisture permeability, having awater entry pressure of 2300 mmH₂ O/cm² and a moisture-vaportransmission of 5400 g/m² ·24 hrs. Besides, the peeling strength and thecrease-flex-resistance were high, 370 g/cm and more than 3000 times/1 kgload, respectively. These physical properties were little deterioratedeven after washing five times. Thus, this product was suitable forvarious water-proof cloths. The section of this product is as shown inFIG. 1.

EXAMPLE 10

15 parts of a polyester type polyurethane elastomer, 8 parts of stearicacid chromic chloride and 5 parts of a pore controller were dissolvedand dispersed in 72 parts of dimethylformamide to prepare a coatingsolution. The coating solution thus prepared was applied onto apre-softened nylon taffeta in an amount of about 200 g/m² using areverse roll coater. Immediately thereafter, the base fabric wasconducted into a water bath containing 10% dimethylformamide andimmersed therein for 5 minutes at 20° C. to allow gelation to takeplace, washed with hot water at 80° C. for 30 minutes, dried with hotair at 120° C. and then heat-treated at 140° C. for 5 minutes to form amicroporous layer of drape texture on the surface of the base fabric.

The base fabric was then immersed in a 3% silicone emulsion, squeezed bya mangle uniformly at a squeeze ratio of 50% and thereafter heat-treatedat 150° C. for 30 seconds using a conventional heat setter.

The resulting product possessed superior water-proofness and moisturepermeability: water entry pressure 1600 mmH₂ O, water repellency 100,moisture-vapor transmission 5300 g/m² ·24 hrs. Besides, its resistanceto washing and to dry cleaning was good.

EXAMPLE 11

17 parts of a polyester type polyurethane elastomer, 5 parts of stearicacid alumic chloride, 3 parts of a silicone-based water repellent agentand 3 parts of an inorganic filler were dissolved and dispersed in 72parts of dimethylformamide to prepare a coating solution.

The coating solution thus prepared was applied onto a polyester twillfabric in an amount of about 150 g/m² using a knife-over-roll coater.The base fabric was conducted into a 10% aqueous dimethylformamidesolution and immersed therein for 5 minutes at 30° C., thereafter driedwith hot air at 120° C. and heat-treated at 140° C. for 5 minutes toform a microporous layer of drape handling on the surface of the basefabric.

The base fabric was then immersed in a 5% aqueous dispersion of afluorine-based water repellent agent, thereafter squeezed by a mangleuniformly at a squeeze ratio of 50% and heat-treated at 150° C. for 30seconds using a heat setter.

The resulting product possessed superior water-proofness and moisturepermeability: water entry pressure 2200 mmH₂ O/cm², water repellency100, moisture-vapor transmission 5100 g/m² ·24 hrs. Besides, thesephysical properties were little deteriorated even after washing fivetimes according to the instructions defined by JIS L-0844 (A-2).

In the above Examples, "crease-flex-resistance" means the number ofrubbing when the coated fabric was rubbed at 1 kg load by means of ScottType Folding and Abrading Tester until the surface of the fabric couldbe cracked. The flourine-based repellent agent used together withpolyurethane elastomer is "Scotchguard FC-453" (a product of 3M) and thefluorine-based repellent agent used for pre- or after-treatment is"Asahiguard AG-710" (a product of Meisei Chemical Co.). The polyestertype polyurethane elastomer used is a linear polyurethane obtained byaddition-polymerization of polyester having terminal hydroxy groups ofm.w.2,000, which was obtained by condensation reaction of adipic acidand ethylene glycol, diphenylmethane-4,4'-diisocyanate and a dihydroxycompound such as ethylene glycol. The polyether type polyurethaneelastomer used is a linear polyurethane obtained byaddition-polymerization of polyether having terminal hydroxyl groups ofm.w.2,500, which was obtained by ring-opening-polymerization oftetrahydrofuran, diphenylmethane-4,4'-diisocyanate and hydrazine. In theexamples, the silicone-based repellent agent used together withpolyurethane elastomer is "Toray Silicone SD8,000" (a product of ToraySilicone Company, Limited) and the silicone-based repellent agent usedfor pre- or after-treatment is "Toray Silicone BY-16-805" (A product ofToray Silicone Company, Limited).

We claim:
 1. A moisture-permeable waterproof coated fabric comprising abase fabric and a microporous layer of a synthetic polymer consistingessentially of polyurethane formed on at least one face of said basefabric characterized in that said microporous layer being providedtherewithin with cavity portions communicating with fine pores havingdiameters not larger than 5 microns formed on the surface of saidmicroporous layer, the void portions of said cavity portions havingdiameters at least three times as large as the diameters of said finepores and further characterized in that the inner wall of saidrespective cavity is covered with water repellent agent and at least apart of said inner wall is provided at least a communication hole on itto communicate between adjacent cavities, said microporous layer beingformed from a coating solution of a polar organic solvent containing 8to 25% by weight of a polyurethane elastomer, 0.1 to 10% by weight of awater repellent agent, 0.2 to 3% by weight of polyisocyanate and 1 to 8%by weight of a nonionic surfactant.